The invention is directed to a diaphragm pump comprising a diaphragm or membrane having its outer edge region clamped in a pump housing and driveable in oscillating fashion on the basis of a hydraulic medium, a conveying chamber of the diaphragm pump being separated by the diaphragm from a drive chamber that accepts the hydraulic medium, whereby the diaphragm is composed of two diaphragm disks that are arranged at an axial distance from one another and enclose an interior space whose size is variable given damage to one of the diaphragm disks.
In order to be able to recognize potential damage to the diaphragm in a diaphragm pump, DE-A-18 00 018 discloses that the diaphragm be composed of a plurality of individual diaphragms, for example of three individual diaphragms pressing against one another and that the space between the individual diaphragms be completely filled with hydraulic medium and be connected to a supply reservoir via a conduit equipped with a check valve. Given a rupture of one of the two outer diaphragms, thus, the medium to be conveyed from the conveying chamber or the hydraulic medium from the work chamber can flow into the supply reservoir and thereby trigger the display mechanism.
The line part that connects the space between the individual diaphragms to the supply reservoir comprises only an extremely narrow capillary cross section, at least in the clamping region of the diaphragms that is pressure-tight around 250 bar. Particularly given conveying medium provided with solids particles, this line part consequently clogs easily, leading to the outage of the function of the flow display.
In addition to the considerable structural outlay of this design, the display means is extremely insensitive since it responds to a level change of the hydraulic medium in the supply reservoir, what is particularly of further disadvantage is that a relatively large quantity of the hydraulic medium situated in the space between the diaphragms and in the conduit connecting this space to the supply reservoir proceeds therefrom into the conveyed medium given damage to the individual diaphragm facing toward the conveying chamber. This can lead to considerable down times as well as to the production of rejects, so that the smooth execution of a continuous manufacture deteriorates greatly. For example, in this type of monitoring, the diaphragm rupturing can therefore not be utilized in paint sprayer devices, particularly since a recognition of rupture only becomes possible when one of the two outer diaphragms is damaged to such an extent that conveyed or hydraulic medium additionally proceeds into the component parts allocated to the display means.